Defending champion Matteo Berrettini edged Denis Kudla 3-6, 7-6 (5), 6,4 on Thursday to advance to the Queen’s Club Championship quarterfinal.
The second-seed, who beat Andy Murray in the Stuttgart final on Sunday, fired 22 aces past Kudla as he looks to clinch back-to-back grass-court titles.
Berrettini’s booming serve, which took him to the Wimbledon final last year, eventually bailed him out after Kudla — ranked No. 82 — won the first set without facing a break point.
Three aces from Berrettini helped him win the second-set tiebreaker, after which he called for the trainer.
Berrettini broke for 3-2 in the third set, was immediately broken himself, then benefitted from a unforced error at the net by Kudla — an Ukrainian-born American — to break again for 5-4.
The Italian saved a break point in the next game, during which he sent down a serve at 140mph (225mph), and clinched the match at the first attempt with a winner from a backhand volley.
Earlier in the day, Tommy Paul eased to 6-1, 6-4 victory against 16-time ATP title winner Stan Wawrinka.
Paul wrapped up the first set in 29 minutes, continuing his impressive form which also saw him beat sixth-seeded Denis Shapovalov in the first round.
Information from Associated Press was included in this report.